Wire up createViewTransitionInstance in Fabric

packages/react-native-renderer/src/ReactFiberConfigFabric.js

@@ -90,6 +90,11 @@ const {get: getViewConfigForType} = ReactNativeViewConfigRegistry;
 // % 2 === 0 means it is a Fabric tag.
 // This means that they never overlap.
 let nextReactTag = 2;
+export function allocateTag(): number {
+  const tag = nextReactTag;
+  nextReactTag += 2;
+  return tag;
+}
 
 type InternalInstanceHandle = Object;
 
@@ -184,8 +189,7 @@ export function createInstance(
   hostContext: HostContext,
   internalInstanceHandle: InternalInstanceHandle,
 ): Instance {
-  const tag = nextReactTag;
-  nextReactTag += 2;
+  const tag = allocateTag();
 
   const viewConfig = getViewConfigForType(type);
 
@@ -235,8 +239,7 @@ export function createTextInstance(
     }
   }
 
-  const tag = nextReactTag;
-  nextReactTag += 2;
+  const tag = allocateTag();
 
   const node = createNode(
     tag, // reactTag

packages/react-native-renderer/src/ReactFiberConfigFabricWithViewTransition.js

@@ -16,8 +16,11 @@ import type {
   GestureTimeline,
 } from './ReactFiberConfigFabric';
 
+import {allocateTag} from './ReactFiberConfigFabric';
+
 const {
   applyViewTransitionName: fabricApplyViewTransitionName,
+  createViewTransitionInstance: fabricCreateViewTransitionInstance,
   startViewTransition: fabricStartViewTransition,
 } = nativeFabricUIManager;
 
@@ -196,6 +199,8 @@ export function addViewTransitionFinishedListener(
 export function createViewTransitionInstance(
   name: string,
 ): ViewTransitionInstance {
+  const tag = allocateTag();
+  fabricCreateViewTransitionInstance(name, tag);
   return {
     name,
     old: new (ViewTransitionPseudoElement: any)('old', name),

scripts/flow/react-native-host-hooks.js

@@ -306,6 +306,7 @@ declare const nativeFabricUIManager: {
     name: string,
     className: ?string,
   ) => void,
+  createViewTransitionInstance: (name: string, tag: number) => void,
   startViewTransition: (mutationCallback: () => void) => {
     finished: Promise<void>,
     ready: Promise<void>,